Pressure Sensitivity Research Articles

A multifunctional hydrogel-based strain sensor and triboelectric nanogenerator for running monitoring and energy harvesting

Recently, flexible wearable electronics for human running posture monitoring and human energy harvesting have attracted widespread attention. Hence, we design a mixed type conductive hydrogel based on polyvinyl alcohol, cotton paper, graphite oxide, and MXene, named PCGM hydrogel. Furthermore, the PCGM hydrogel can act as the PCGM-based strain sensor and triboelectric nanogenerator (P-TENG) for running posture monitoring and mechanical energy harvesting. The PCGM-based strain sensor has two sensing linear regions: The pressure sensitivity is 0.0164 kPa−1 in the low pressure region (0–16 kPa), whereas it is 0.002 86 kPa−1 in the high pressure region (16–120 kPa). To achieve comprehensive health monitoring of runners, the PCGM-based strain sensors can be installed on human joints and facial skin to monitor human posture and facial expressions. The PCGM hydrogel can be combined with a polytetrafluoroethylene film to form a P-TENG device for mechanical energy harvesting. The P-TENG maximum output power can reach 135 µW with a 30 MΩ load. The short-circuit current (Isc), open-circuit voltage (Voc), and transfer charge (Qsc) of P-TENG can reach 10.36 µA, 229.85 V, and 49.24 nC, respectively. This research provides an effective approach for human-running motion monitoring by using multifunctional flexible devices.

Highly Sensitive SAW Pressure Sensor Based on Simply Supported Beam

In this work, a SAW pressure sensor based on a simply supported beam was designed and fabricated. The SAW resonator deposited on 128° YX-lithium niobate (LNO) substrate was used as the sensing element. The LNO substrate was used as a simply supported beam, therefore strain transfer loss was avoided and uniaxial stress was directly applied to the SAW resonator. An indenter with two ledges was used to indent the LNO beam and then uniform strain was applied to the SAW resonator. The sensitivity was experimentally measured in a pressure range of 330 kPa. The results demonstrated that the sensitivity of the SAW pressure sensor in this work was as high as 2514 ppm/MPa. The high pressure sensitivity of the proposed SAW pressure sensor was analyzed. The device structure of the proposed SAW pressure sensor may help to design highly sensitive SAW pressure sensors.

Distributed and polarimetric pressure sensitivity in spun highly birefringent optical fibers.

We examine experimentally the influence of the fiber inelastic twist on polarimetric sensitivity to hydrostatic pressure and pressure sensitivity in a Rayleigh-scattering-based optical frequency-domain reflectometer (OFDR) for highly birefringent side-hole fibers. The fibers were drawn from the same preform with different spin pitches varying from 5 mm to 200 mm. We also demonstrate that the sensitivities of spun fiber can be estimated analytically based on its spin pitch, measured birefringence, and the sensitivity of the corresponding non-twisted fiber, showing good agreement with the experimental results. We proved that polarimetric sensitivity to pressure decreases with the shorter spin pitches, while distributed pressure sensitivity decreases for the one polarization eigenmode and increases for the second polarization eigenmode. Therefore, the spun-fibers can operate well as the polarimetric sensors of other physical parameters inducing circular birefringence even under varying pressure. Moreover, they can be used to obtain the desired difference between sensitivities for both polarization eigenmodes.

Salt Sensitivity of Blood Pressure in Black People: The Need to Sort Out Ancestry Versus Epigenetic Versus Social Determinants of Its Causation.

Race is a social construct, but self-identified Black people are known to have higher prevalence and worse outcomes of hypertension than White people. This may be partly due to the disproportionate incidence of salt sensitivity of blood pressure in Black people, a cardiovascular risk factor that is independent of blood pressure and has no proven therapy. We review the multiple physiological systems involved in regulation of blood pressure, discuss what, if anything is known about the differences between Black and White people in these systems and how they affect salt sensitivity of blood pressure. The contributions of genetics, epigenetics, environment, and social determinants of health are briefly touched on, with the hope of stimulating further work in the field.

ZnO-poly(acrylonitrile) composite films with improved piezoelectric properties for energy harvesting and sensing applications

Piezoelectric nanogenerators are one of the possible solutions for generating power in milliwatts for various mobility applications. They can also be utilized as tactile sensors. Since poly(acrylonitrile) (PAN) has a greater dipole moment (3.5 D) than poly (vinylidene fluoride) (PVDF), it has a strong potential for use as piezoelectric nanogenerators and pressure sensors. However, due to strong dipole-dipole repulsion, the nitrile groups are difficult to align in a zig-zag configuration resulting in reduced ability of the system to convert mechanical energy into electrical energy. To address this issue, we have incorporated ZnO nanoparticles (ZnP) and ZnO nanowires (ZnW) in PAN films. Due to the strong interaction of ZnO nanostructures with PAN, the dipole-dipole repulsion reduces resulting in increased zigzag conformation of PAN. Compared to ZnP, ZnW was found to show better alignment of PAN nitrile groups and faster relaxation of dipoles after removal of stress. Without any external poling, PAN, ZnP-PAN, and ZnW-PAN films based piezoelectric nanogenerators could generate 27.6, 79.3 and 86.3 mW/m2 of power, respectively. The incorporation of 5 wt% ZnP and ZnW also significantly improved the pressure sensitivities of the devices to 0.9 fFPa−1 and 1.1 fFPa−1, respectively, as compared to 0.1 fFPa−1 for pristine PAN film.

Mechanistic study of the influence of aluminum nanoparticles on the pressure sensitivity of 1,3,5-trinitro1,3,5-triazinane (RDX) thermal decomposition

The incorporation of Al nanoparticles (Al NPs) into 1,3,5-trinitro1,3,5-triazinane (RDX) can catalyze its thermal decomposition and reduce the pressure exponent (n) of solid propellants. However, the underlying reaction mechanism at a deeper level remains unclear. In this study, the reaction processes of Al NPs catalyzing the thermal decomposition of RDX under different initial pressures were investigated by utilizing the ReaxFF molecular dynamics (ReaxFF-MD) simulations combined with DFT calculations, and the influence mechanism of Al NPs on the pressure sensitivity of RDX thermal decomposition was revealed from various perspectives. In the initial stage of the reaction, unlike the nitro group dissociation observed in pure RDX, the incorporation of Al NPs alters the initial decomposition pathway of RDX, making it more easily adsorbed on the surface of Al and enhancing the early-stage decomposition rate. Furthermore, Al NPs exhibit higher catalytic activity in low-pressure systems. In the later stage, because of the massive adsorption of free radicals generated from RDX decomposition on the surface of Al NPs, the decomposition rate of RDX decreases significantly, especially in high-pressure systems. Consequently, Al NPs synergistically reduce the pressure sensitivity of the RDX thermal decomposition from two different perspectives. Compared to traditional experimental research or single RDX simulation studies, this work further explores the interaction between Al and RDX from a microscopic perspective, addressing the gap in the field of the influence mechanisms of Al NPs on the pressure sensitivity of RDX thermal decomposition. It also establishes a theoretical foundation for the practical application of Al@RDX fuels.

High-fidelity optical fiber microphone based on graphene oxide and Au nanocoating

Abstract A high-fidelity optical fiber microphone (HF-OFM) with hybrid frequency and fast response is theoretically and experimentally demonstrated by the nanofabrication techniques for real-time communication, which consists of a graphene oxide (GO) film, an Au nanocoating, and an air cavity. The internal stress of the film is increased by the method of mechanical tensile preparation, and the microphone response flatness is improved. Meanwhile, the structural design of the 3 nm Au nanocoating improves the acoustic pressure detection sensitivity by 2.5 times by increasing the reflectivity. The experimental result shows that single, dual, and triple frequency acoustic signal detection in the frequency range of 0.1 kHz–20 kHz are achieved with acoustic pressure sensitivities of 9.64, 9.66, and 8.9 V/Pa, as well as flat frequency response (<2 dB variation). The minimum detectable pressure (MDP) at 1 kHz is 63.25 μPa/Hz1/2. In addition, the high-fidelity real-time transmission of audio signals over an angle range of −90° to 90° is verified by a self-made acoustic pressure detection device. Such a compact, high sensitivity, and large measurement range HF-OFM is very promising for applications of oil leakage exploration, acoustic source location, and real-time communication.

Armadillo-inspired ultra-sensitive flexible sensor for wearable electronics

Flexible sensors are receiving growing attention as a valuable technology in application areas such as wearable electronics, soft robotics and e-skin. Unfortunately, most flexible sensors generally suffer from low sensitivity, narrow application range and single detection function. Herein, we present an uneven deformation strategy inspired by armadillo skin to construct ultra-sensitive flexible sensors. ASR-CLNS sensor consists of a silicone rubber substrate imitating the armadillo skin (ASR) and a continuously laminated conductive network (CLN). Mechanical deformation-induced stress concentration substantially contributes to ultra-high sensitivity. Noteworthily, the non-uniform substrates have specific stress concentration responses in different tensile directions, and the stretch sensitivity can be easily adjusted by microstructure customization or simply changing the sensor placement angle, which enables it to meet the detection requirements of more scenarios. Simultaneously, the laminated structure of the CLN endows the sensor pressure sensitivity, which allows sensors to be used to detect small pressures such as human breathing. Additionally, CLN demonstrated fast heat transfer capability, which can effectively improve the thermal management properties of composites. In short, this work provides an unexplored strategy to develop tunable/ultra-high sensitivity and multifunctional flexible sensor devices.

Salt Sensitivity: Causes, Consequences, and Recent Advances.

Salt (sodium chloride) is an essential nutrient required to maintain physiological functions. However, for most people, daily salt intake far exceeds their physiological need and is habitually greater than recommended upper thresholds. Excess salt intake leads to elevation in blood pressure which drives cardiovascular morbidity and mortality. Indeed, excessive salt intake is estimated to be responsible for ≈5 million deaths per year globally. For approximately one-third of otherwise healthy individuals (and >50% of those with hypertension), the effect of salt intake on blood pressure elevation is exaggerated; such people are categorized as salt sensitive and salt sensitivity of blood pressure is considered an independent risk factor for cardiovascular disease and death. The prevalence of salt sensitivity is higher in women than in men and, in both, increases with age. This narrative review considers the foundational concepts of salt sensitivity and the underlying effector systems that cause salt sensitivity. We also consider recent updates in preclinical and clinical research that are revealing new modifying factors that determine the blood pressure response to high salt intake.

Pressure pain sensitivity, thermographic changes, function, life and sleep quality in patients with unilateral rotator cuff injury: A case-control study

Introduction-AimThis study aimed to assess pressure pain sensitivity, thermographic changes, functional status, quality of life, and sleep in individuals with unilateral shoulder pain due to rotator cuff tear and compare these parameters with the unaffected side and asymptomatic individuals. Material-methodThirty-two patients with unilateral rotator cuff injury and 32 volunteers without shoulder problems were included. Pain was evaluated using a visual analogue scale, pressure pain sensitivity with a digital algometer, thermographic changes with a thermal camera, upper extremity function through the Disabilities of the Arm, Shoulder, and Hand Disability Questionnaire, sleep quality using the Pittsburgh Sleep Quality Index, and quality of life using SF-36. ResultsPressure pain sensitivity of the deltoideus, supraspinatus, and subscapularis muscles in the affected limb was lower than in the unaffected limb (p = 0.027, p = 0.005, p < 0.001). Conversely, pressure sensitivity of the deltoideus, biceps brachii, and subscapularis muscles was higher in the patient group (p = 0.008, p = 0.042, p < 0.001). Furthermore, a decrease in temperature was observed in all patients, except for the trapezius muscles of the affected side (p < 0.05). ConclusionThis study sheds light on altered pressure pain sensitivity and thermographic changes in individuals with unilateral shoulder pain due to rotator cuff tear. Additionally, the study highlights impairments in functional status, quality of life, and sleep in these individuals, emphasizing the broader impact of such injuries. Targeted interventions based on these findings have the potential to enhance overall well-being and functional outcomes for affected individuals. Level of evidenceLevel III, Case-control study, prognosis study.

Theoretical study of novel oxazine energetic compounds: Enthalpy of formation, detonation performance, and sensitivity

16 energetic compounds containing oxadiazine ring (1–8, 1 N-8 N) were designed and the structure was optimized by DFT-B3LYP-D3 (BJ) method. The value of the density, enthalpy of formation, burst pressure, and impact sensitivity (IS) (h50 values) were calculated, and a feasible synthesis path was designed by additional condensation and dehydration etherification. The results showed that the oxadiazine ring in the designed compound has a nonplanar structure, which is a six-membered ring in a boat conformation. The enthalpy of formation (1673.20, 1504.68, 1629.22 kJ/mol) of compounds 3 N, 5 N, and 7 N, as well as the detonation performance (D: 8.75, 8.20, 8.46 km/s; p: 35.11, 30.01, 32.24 GPa) and impact sensitivity (h50: 46.80, 46.25, 40.07 cm) were better than that of the others, having the potential as energetic compounds. This research provides a certain theoretical basis for the efficient synthesis and application of such compounds.

Sound source direction-of-arrival estimation method for microphone array based on ultra-weak fiber Bragg grating distributed acoustic sensor.

A sound source direction-of-arrival (DOA) estimation method for microphone array based on ultra-weak fiber Bragg grating (UW-FBG) distributed acoustic sensor is proposed. The principle of acoustic signal demodulation is introduced, the sound pressure sensitivity and frequency response range of a single UW-FBG microphone are analyzed, and a series linear array with three UW-FBG microphones is designed. Combined with convolutional recurrent neural networks, the DOA estimation method is developed. Log-Mel spectral features and SCOT/PHAT joint weighting generalized cross correlation features are used for DOA estimation. The corresponding system is established and experimentally verified. Results show that the measured sound pressure sensitivity of the UW-FBG microphone is in the range of 0.1032-3.306 rad/Pa within the frequency range of 1000-3000 Hz, and the peak sound pressure sensitivity is about 3.306 rad/Pa. The estimated mean error of 2D DOA estimation is about 2.85°, and the error of 3D DOA estimation is about 5.465°. This method has good application prospects in distributed sound source localization.

Abstract 012: Diagnosis Of Salt Sensitivity Of Blood Pressure Using Circulating Monocyte Isolevuglandin-CXCL/CCL Signaling In Response To Elevated Sodium In Vitro

Salt sensitivity of blood pressure (SSBP) is when blood pressure changes parallel to salt loading/ depletion and is an independent risk factor for cardiovascular disease. Despite its importance, there is no feasible diagnosis, which limits investigational studies to identify therapeutic targets. Our studies indicate that changes in production of isolevuglandins (IsoLGs) in antigen presenting cells (APCs) parallel changes in blood pressure following salt-loading and depletion in humans and this is associated with chemokine signaling. We hypothesized that in vivo responses to salt-loading/depletion leading to IsoLG production in APCs are mirrored in vitro . To test this hypothesis, we isolated peripheral blood mononuclear cells from known salt-sensitive and salt-resistant people and treated them with either normal salt (140 mmoL) or high salt (190 mmoL) for 24 hours in vitro . Using flow cytometry, we found that classical monocytes from salt sensitive but not salt resistant people had a significant increase in IsoLGs (25.15 ± 7.41 vs 14.52 ± 8.60, p = 0.0022) after 24 hours of high salt treatment. To determine mechanisms, we also performed bulk RNAseq on in vitro high salt treated monocytes and CITEseq on PBMCs following the salt-loading/depletion protocol. We found that salt-loading/depletion was associated with parallel changes in the expression of various chemokines in the CXCL and CC families both in vitro and in vivo . Specifically, the changes in levels of CXCL8 (p = 0.01553, r = 0.8067) , CXCL16 (p = 0.004697, r = -0.8725), and CCL2 (p = 0.002292, r = -0.9004) correlated with changes in diastolic and systolic blood pressure from salt loading to depletion. Moreover, changes in systolic blood pressure significantly correlated with changes in CCL2 (p= 0.008878, r= -0.6302) and CCL4 (p= 0.03209, r = -0.5367) from salt loading to salt depletion. These data suggest that in vitro responses of IsoLGs and chemokine production to salt treatment could serve as a feasible diagnosis for salt sensitivity of blood pressure in the clinic.

A Multi-Yield-Surface Plasticity State-Based Peridynamics Model and its Applications to Simulations of Ice-Structure Interactions

Due to complex mesoscopic and the distinct macroscopic evolution characteristics of ice, especially for its brittle-to-ductile transition in dynamic response, it is still a challenging task to build an accurate ice constitutive model to predict ice loads during ship-ice collision. To address this, we incorporate the conventional multi-yield-surface plasticity model with the state-based peridynamics to simulate the stress and crack formation of ice under impact. Additionally, we take into account of the effects of inhomogeneous temperature distribution, strain rate, and pressure sensitivity. By doing so, we can successfully predict material failure of isotropic freshwater ice,iceberg ice, and columnar saline ice. Particularly, the proposed ice constitutive model is validated through several benchmark tests, and proved its applicability to model ice fragmentation under impacts, including drop tower tests and ballistic problems. Our results show that the proposed approach provides good computational performance to simulate ship-ice collision.

Versatile Optofluidic Fabry-Perot Sensor for Multiple Physical Parameters in Microfluidic Chips

An optofluidic sensor, which is composed of a fiber Fabry-Perot interferometer (FPI) and a microfluidic chip, is experimentally demonstrated to measure aerostatic pressure, local temperature, and fluidic flow rate in microfluidic chips. The aerostatic pressure sensitivity is as high as −2393.3 nm/Bar. By demodulating the aerostatic pressure and temperature with a sensitivity matrix, both the physical parameters can be predicted simultaneously. The noise-equivalent detection limit (NEDL) of aerostatic pressure is as low as 48.4 μBar. In addition, the experiment results show that the fluidic flow rate sensitivity is −1.8574 nm/(μl/min) and the NEDL of fluidic flow rate is 97.1 nl/min, respectively. The miniature optofluidic sensor based on the optical fiber Fabry-Perot interferometer provides a promising cost-effective sensing platform for monitoring multiple physical parameters in the microfluidic chips, which is of great significance for on-chip biochemical reactions.

Dual-Layer All-Textile Flexible Pressure Sensor Coupled by Silver Nanowires with Ti3C2-Mxene for Monitoring Athletic Motion during Sports and Transmitting Information.

At present, wearable flexible pressure sensors have broad application prospects in fields such as motion monitoring and information transmission. However, it is still a challenge to design flexible pressure sensors with high sensitivity over a large sensing range and simple fabrication. Here, we use a simple "dipping-drying" method to fabricate a fabric-based flexible pressure sensor by coupling silver nanowires (AgNWs) with Ti3C2-MXene. The interaction between MXene and AgNWs helps realize a dual-layer sensing network, achieving good synergistic effects between pressure sensitivity and sensing range. The effects of the material combination and dip-coating sequence on the sensor's performance are systematically studied. The results show that the sensor was impregnated sequentially with AgNWs solution, and the MXene solution has the highest sensitivity (0.168 kPa-1) over a wide range (190 kPa). Meanwhile, it has the advantages of low response hysteresis and detection limit, as well as good linearity and durability. We further demonstrate the application of this sensor in human physiological signal monitoring and motion pattern recognition. It can also encrypt and transmit information according to different pressing states. In addition, the proposed pressure sensor array exhibits spatial resolution detection capabilities, laying the foundation for applications in the fields of motion monitoring and human-computer interaction.

A Highly Sensitive Iontronic Bimodal Sensor with Pressure‐Temperature Discriminability for Robot Skin

Iontronic sensors, with the electrical double layer effect at the iontronic film /electrode interface as well as the temperature‐sensitive characteristic of the iontronic film, demonstrate the potential to be robot skin with pressure‐temperature perception. Herein, a highly sensitive iontronic bimodal sensor (IBS) with pressure‐temperature discriminability for robot skin is reported. With the elaborate design of the structure, especially the reasonable arrangement of electrodes, the resistance‐capacitance dual‐measurement modes on the iontronic film are realized. Based on the temperature‐sensitive resistance of the iontronic film, together with a pressure‐sensitive normalized variable of the capacitance of the IBS, a pressure‐temperature decoupling strategy is proposed, terminating in the maximum temperature error of 1.6% in 20–80 °C and the maximum force error of 5.9% in 3–10 N. Moreover, the hierarchically compressible microstructure of the iontronic film, with slender protrusions and stubby protrusions, is readily prepared, empowering the IBS with a pressure sensitivity of 25.9 kPa−1 and a broad pressure range up to 796 kPa. The IBS and the 5 × 5 IBS array, function as the skin for a robot in the scenarios of temperature sensing, writing calligraphy, and object manipulation, manifesting gigantic potential in human‐robot interaction.

Composite Flexible Sensor Based on Bionic Microstructure to Simultaneously Monitor Pressure and Strain.

To achieve the human sense of touch, a strain sensor needs to be coupled with a pressure sensor to identify the compliance of the contacted material. However, monitoring the pressure-strain signals simultaneously and ensuring no coupling effect between the two signals is the technical bottleneck for the flexible tactile sensor to. Herein, a composite flexible sensor based on microstructures of lotus leaf is designed and manufactured, which integrates the capacitive pressure sensor and the resistance strain sensor into one pixel to realize the simultaneous detection of pressure and strain. The electrode layer of the capacitance sensor also plays the role of the resistance strain sensor, which greatly simplifies the structure of the composite flexible sensor and obtains the compact size to integrate more easily. The device can simultaneously detect pressure and deformation, and more importantly, there is no coupling effect between the two kinds of signals. Here, the sensor has high pressure sensitivity (0.784kPa-1 when pressure less than 100kPa), high strain sensitivity (gauge factor=4.03 for strain 0-40%), and can identify materials with different compliance, which indicates the tactile ability as the human skin performs.

Intrinsically Stretchable Conductive Self-Healable Organogels for Strain, Pressure, Temperature, and Humidity Sensing.

Intrinsically stretchable conductive self-healable organogels containing poly(lipoic acid), Al3+ ion, tannic acid, and reduced graphene oxide are produced in this report. These noncovalent networks interlocked through physical (hydrogen and coordination) bonds offered high stretchabilities and mechanical strengths as well as fast self-healing behaviors. The optimum organogel-based sensor showed outstanding pressure sensitivities (0.94 kPa-1 up to 10 and 1.07 kPa-1 for 10-50 kPa) and high strain responses (corresponding gauge factors of 1.1 and 0.4 for 0-50 and 50-100% stretching ratios). This organogel also revealed high stabilities at ambient atmosphere due to the presence of binary solvents of dimethyl sulfoxide and glycerol. Additionally, this stretchable thermistor displayed remarkable two-stage sensitivities of -2.6 and -0.4%/°C ranging over 0-30 and 30-80 °C, respectively. Besides, the signal variations of water droplet addition and removal with different temperatures were recorded by the organogel sensor to elucidate the practical applicabilities as a temperature sensor. Moreover, the organogel was utilized to demonstrate humidity sensing, where individual sensitivities of 0.89 and 0.55 were obtained in the respective relative humidity ranges of 10-30 and 40-90%. In the meanwhile, the sensor device illustrated distinct humidity signals during respiration monitoring of nose and mouth breathing detection. Accordingly, these quad-functional sensor applications in strain, pressure, temperature, and humidity detection enable this gel to act as a promising material for future multifunctional flexible electronics.

High-sensitivity fiber optic Fabry-Perot ultrasonic sensor based on a grooved silicon diaphragm for partial discharge detection.

An extrinsic fiber optic Fabry-Perot interferometric (EFPI) ultrasonic sensor based on a grooved silicon diaphragm for partial discharge (PD) detection has been proposed. The size of the groove is determined by finite element simulation, which allows the resonant frequency of the sensor to meet the requirements of PD ultrasonic detection and improves the sensitivity of the sensor by 5.07 times compared with that based on a traditional circular diaphragm. The microelectro-mechanical system process is used to fabricate the diaphragm on a silicon-on-insulator wafer, and the prepared diaphragm has a grooved section with a diameter of 829.34µm and a thickness of only 2.09µm. At its resonant frequency of 61.5kHz, the acoustic pressure sensitivity of the sensor is 172.42mV/Pa. The ultrasonic signal detection capability of the sensor is verified in the PD experiment. Furthermore, the characteristics of the corona discharge are successfully manifested based on the ultrasonic waves detected by the EFPI sensor. It is demonstrated that the proposed sensor is suitable for PD detection due to its high sensitivity, simple production process, and good resistance to environmental interference.